1. Field of the Invention
The present invention relates to electrical connectors, more particularly to electrical connectors with additional mating ports for mating with corresponding connectors.
2. Description of Related Art
Personal computers (PC) are used in a variety of ways for providing input and output. Universal Serial Bus (USB) is a serial bus standard to the PC architecture with a focus on computer telephony interface, consumer and productivity applications. The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standard body incorporating leading companies from the computer and electronic industries. USB can connect peripherals such as mouse devices, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, external storage, networking components, etc. For many devices such as scanners and digital cameras, USB has become the standard connection method.
As of 2006, the USB specification was at version 2.0 (with revisions). The USB 2.0 specification was released in April 2000 and was standardized by the USB-IF at the end of 2001. Previous notable releases of the specification were 0.9, 1.0, and 1.1. Equipment conforming to any version of the standard will also work with devices designed to any previous specification (known as: backward compatibility).
USB supports three data rates: 1) A Low Speed rate of up to 1.5 Mbit/s (187.5 KB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks; 2) A Full Speed rate of up to 12 Mbit/s (1.5 MB/s); (Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed); 3) A Hi-Speed rate of up to 480 Mbit/s (60 MB/s). Though Hi-Speed devices are commonly referred to as “USB 2.0” and advertised as “up to 480 Mbit/s”, not all USB 2.0 devices are Hi-Speed. Hi-Speed devices typically only operate at half of the full theoretical (60 MB/s) data throughput rate. Most Hi-Speed USB devices typically operate at much slower speeds, often about 3 MB/s overall, sometimes up to 10-20 MB/s. A data transmission rate at 20 MB/s is sufficient for some but not all applications. However, under a circumstance transmitting an audio or video file, which is always up to hundreds MB, even to 1 or 2 GB, currently transmission rate of USB is not sufficient.
FIGS. 12 to 15 show existing USB 2.0 connectors. In FIGS. 12 to 14, this USB connector is a standard B-type USB 2.0 receptacle 300. The USB 2.0 receptacle 300 commonly is an integral part of a host or PC. The USB 2.0 receptacle 300 includes a plug-receiving cavity 31, a receptacle tongue plate portion 32 extending into the cavity 31, a plurality of contacts 33 supported by the receptacle tongue plate portion 32, and a metal shield 34 shielding the cavity 31. The tongue plate portion 32 defines a plurality of passageways (not labeled) for receiving the contacts 33. The contacts 33 are located at opposite sides of the tongue plate portion 32. Each contact 33 includes a convex shaped contact section 331 protruding into the cavity 31 for mating with corresponding plug. The USB 2.0 receptacle 300 further has a pair of beveled portions 35, 36 respectively formed on the upper left corner and the upper right corner of the cavity 31 as best shown in FIG. 13.
FIG. 15 shows a standard B-type USB 2.0 plug 400 for mating with the standard USB 2.0 receptacle 300. The USB 2.0 plug 400 includes a plug insulator 41 defining an opening 42, a plurality of contacts 43 retained in the plug insulator 41, and a metal shell 44 enclosing the plug insulator 41. The plug insulator 41 includes an upper wall 411 and a lower wall 412 with the opening 42 formed therebetween. The contacts 43 are plate-shaped and non-elastic in order to be retained on inner surfaces of the upper and lower walls 411, 412, respectively. The USB 2.0 plug 400 further includes a pair of slant portions 45, 46 located on top lateral sides thereof for mating with the corresponding beveled portions 35, 36 of the USB 2.0 receptacle 300 in order to guide correct insertion of the USB 2.0 plug 400.
As discussed above, with limited data transmission speed of the USB 2.0 connectors, there is a need to design electrical connectors with additional mating ports for high-speed signal transmission.